In 2005, Patek launched ref 5250 and introduced the Silinvar escape wheel
In 2006 Patek launched ref 5350 and added the spiromax balance spring in Silinvar
In 2008, Patek launched ref 5450 and added the Pulsomax escape, the anchor
You have to remember that the escape system is composed of 3 parts: the wheel, the spiral and the anchor
All these references were annual calendar and they concluded by a perpetual calendar (5550P)
and for the first time, the GyromaxSi balance wheel